Prepare SimpleIndexSaver for index flush thread.

3 files changed, 51 insertions, 14 deletions

diff --git a/searchlib/src/vespa/searchlib/predicate/simple_index.hpp b/searchlib/src/vespa/searchlib/predicate/simple_index.hpp
index 5c5afedfe90..5d2380b523d 100644
--- a/searchlib/src/vespa/searchlib/predicate/simple_index.hpp
+++ b/searchlib/src/vespa/searchlib/predicate/simple_index.hpp
@@ -108,18 +108,18 @@ SimpleIndex<Posting, Key, DocId>::deserialize(vespalib::DataBuffer &buffer, Post
 template <typename Posting, typename Key, typename DocId>
 void
 SimpleIndex<Posting, Key, DocId>::addPosting(Key key, DocId doc_id, const Posting &posting) {
-    auto iter = _dictionary.find(key);
+    auto iter = _dictionary.lowerBound(key);
     vespalib::datastore::EntryRef ref;
-    if (iter.valid()) {
+    if (iter.valid() && key == iter.getKey()) {
         ref = iter.getData();
         insertIntoPosting(ref, key, doc_id, posting);
         if (ref != iter.getData()) {
-            std::atomic_thread_fence(std::memory_order_release);
+            _dictionary.thaw(iter);
             iter.writeData(ref);
         }
     } else {
         insertIntoPosting(ref, key, doc_id, posting);
-        _dictionary.insert(key, ref);
+        _dictionary.insert(iter, key, ref);
     }
 }
 
@@ -147,9 +147,9 @@ SimpleIndex<Posting, Key, DocId>::removeFromPostingList(Key key, DocId doc_id) {
     _btree_posting_lists.remove(ref, doc_id);
     removeFromVectorPostingList(ref, key, doc_id);
     if (!ref.valid()) { // last posting was removed
-        _dictionary.remove(key);
+        _dictionary.remove(dict_it);
     } else if (ref != original_ref) {  // ref changed. update dictionary.
-        std::atomic_thread_fence(std::memory_order_release);
+        _dictionary.thaw(dict_it);
         dict_it.writeData(ref);
     }
     return std::make_pair(posting, true);
@@ -304,7 +304,7 @@ template <typename Posting, typename Key, typename DocId>
 std::unique_ptr<ISaver>
 SimpleIndex<Posting, Key, DocId>::make_saver(std::unique_ptr<PostingSaver<Posting>> subsaver) const
 {
-    return std::make_unique<SimpleIndexSaver<Posting, Key, DocId>>(_dictionary, _btree_posting_lists, std::move(subsaver));
+    return std::make_unique<SimpleIndexSaver<Posting, Key, DocId>>(_dictionary.getFrozenView(), _btree_posting_lists, std::move(subsaver));
 }
 
 }
diff --git a/searchlib/src/vespa/searchlib/predicate/simple_index_saver.h b/searchlib/src/vespa/searchlib/predicate/simple_index_saver.h
index eefaf7c79f4..53357187d54 100644
--- a/searchlib/src/vespa/searchlib/predicate/simple_index_saver.h
+++ b/searchlib/src/vespa/searchlib/predicate/simple_index_saver.h
@@ -4,6 +4,7 @@
 
 #include "i_saver.h"
 #include "simple_index.h"
+#include <vespa/vespalib/stllike/allocator.h>
 
 namespace search::predicate {
 
@@ -15,15 +16,20 @@ template <typename Posting,
           typename Key = uint64_t, typename DocId = uint32_t>
 class SimpleIndexSaver : public ISaver
 {
+    using EntryRef = vespalib::datastore::EntryRef;
     using Source = SimpleIndex<Posting,Key,DocId>;
-    using Dictionary = Source::Dictionary;
+    using Dictionary = Source::Dictionary::FrozenView;
+    using FrozenRoots = std::vector<EntryRef, vespalib::allocator_large<EntryRef>>;
     using BTreeStore = Source::BTreeStore;
 
-    const Dictionary& _dictionary;
+    const Dictionary  _dictionary;
+    FrozenRoots       _frozen_roots;
     const BTreeStore& _btree_posting_lists;
     std::unique_ptr<PostingSaver<Posting>> _subsaver;
+
+    void make_frozen_roots();
 public:
-    SimpleIndexSaver(const Dictionary& dictionary, const BTreeStore& btree_posting_lists, std::unique_ptr<PostingSaver<Posting>> _subsaver);
+    SimpleIndexSaver(Dictionary dictionary, const BTreeStore& btree_posting_lists, std::unique_ptr<PostingSaver<Posting>> _subsaver);
     ~SimpleIndexSaver() override;
     void save(BufferWriter& writer) const override;
 };
diff --git a/searchlib/src/vespa/searchlib/predicate/simple_index_saver.hpp b/searchlib/src/vespa/searchlib/predicate/simple_index_saver.hpp
index a3db21ca6cb..327d5440346 100644
--- a/searchlib/src/vespa/searchlib/predicate/simple_index_saver.hpp
+++ b/searchlib/src/vespa/searchlib/predicate/simple_index_saver.hpp
@@ -6,11 +6,13 @@
 namespace search::predicate {
 
 template <typename Posting, typename Key, typename DocId>
-SimpleIndexSaver<Posting, Key, DocId>::SimpleIndexSaver(const Dictionary& dictionary, const BTreeStore& btree_posting_lists, std::unique_ptr<PostingSaver<Posting>> subsaver)
-    : _dictionary(dictionary),
+SimpleIndexSaver<Posting, Key, DocId>::SimpleIndexSaver(Dictionary dictionary, const BTreeStore& btree_posting_lists, std::unique_ptr<PostingSaver<Posting>> subsaver)
+    : _dictionary(std::move(dictionary)),
+      _frozen_roots(),
       _btree_posting_lists(btree_posting_lists),
       _subsaver(std::move(subsaver))
 {
+    make_frozen_roots();
 }
 
 template <typename Posting, typename Key, typename DocId>
@@ -23,9 +25,16 @@ SimpleIndexSaver<Posting, Key, DocId>::save(BufferWriter& writer) const
     assert(sizeof(Key) <= sizeof(uint64_t));
     assert(sizeof(DocId) <= sizeof(uint32_t));
     nbo_write<uint32_t>(writer, _dictionary.size());
-    for (auto it = _dictionary.begin(); it.valid(); ++it) {
+    auto& allocator = _btree_posting_lists.getAllocator();
+    auto frozen_roots_it = _frozen_roots.begin();
+    using PostingIterator = BTreeStore::ConstIterator;
+    for (auto it = _dictionary.begin(); it.valid(); ++it, ++frozen_roots_it) {
         vespalib::datastore::EntryRef ref = it.getData();
-        auto posting_it = _btree_posting_lists.begin(ref);
+        /*
+         * Use copy of frozen root if valid, otherwise use ref from
+         * frozen dictionary.
+         */
+        auto posting_it = frozen_roots_it->valid() ? PostingIterator(*frozen_roots_it, allocator) : _btree_posting_lists.begin(ref);
         nbo_write<uint32_t>(writer, posting_it.size());  // 0 if !valid()
         if (!posting_it.valid())
             continue;
@@ -35,6 +44,28 @@ SimpleIndexSaver<Posting, Key, DocId>::save(BufferWriter& writer) const
             _subsaver->save(posting_it.getData(), writer);
         }
     }
+    assert(frozen_roots_it == _frozen_roots.end());
+}
+
+template <typename Posting, typename Key, typename DocId>
+void
+SimpleIndexSaver<Posting, Key, DocId>::make_frozen_roots()
+{
+    /*
+     * Compensate for lacking snapshot property in
+     * vespalib::btree::BTreeStore.  Traverse frozen dictionary in writer
+     * thread and make a copy of frozen btree roots.
+     */
+    _frozen_roots.reserve(_dictionary.size());
+    for (auto it = _dictionary.begin(); it.valid(); ++it) {
+        auto ref = it.getData();
+        if (ref.valid() && _btree_posting_lists.isBTree(ref)) {
+            _frozen_roots.emplace_back(_btree_posting_lists.getTreeEntry(ref)->getFrozenRootRelaxed());
+            assert(_frozen_roots.back().valid());
+        } else {
+            _frozen_roots.emplace_back();
+        }
+    }
 }
 
 }